I'm guessing your pump has 2 bulbs? Then it had one ballast for each bulb? Possibly the ballast from Menards was for two bulbs? (Thus all the wires?)I'm not sure how old a 3012 pump is but I'm surprised it uses T8(smaller diameter) bulbs.
Yes, 2 bulbs. I am assuming T8s are the correct size as that is what was in there and they fit.
In doing some "Googling" I think the ones from Menards are electronic ballasts and I need the older magnetic ballasts that uses starters (FS-2). Not an electrician so looking to cut as few wires as possible. The other magnetic ballasts I have found on eBay, etc are much smaller than what is in my pump so I am not sure that they would work.
I am guessing my Bennett is early 60s? Square body but has a provision to add a globe.